The present invention relates to a solid magnetic memory and more particularly to a Bloch line memory device suitable to realize a large capacity solid file memory.
A previously well known technique for erasing stored information in the Bloch line memory device is disclosed in U.S. Pat. No. 4,583,200 to Konishi et al issued Apr. 15, 1986. This technique erases information by shifting a to-be-erased Bloch line pair to the end portion of a stripe magnetic domain constituting a storage loop and thereafter chopping the end portion to extrude the to-be-erased Bloch line out of the stripe magnetic domain.
The conventional Block line memory device is constituted as schematically shown in FIG. 1. More specifically, the conventional Bloch line memory device is constituted by a chip 12, a magnetic circuit 16 for generating a magnetic field necessary to operate the chip, and a controller 17 for controlling the operation of the chip 12. The chip 12 includes an information writing/propagation line (major line) conductor 14 which is provided with a bubble generator 19 formed on a magnetic garnet substrate through a predetermined fabrication process, an information read-out/propagation line (major line) conductor 15 provided with a bubble erasure portion 18 and a number of stripe magnetic domains 13 serving as storage loops located in the substrate. In operation, information is converted into the presence or absence of a magnetic bubble 20 on the information writing/propagation line 14 by the controller 17, which, in turn, is converted into the presence or absence of a Bloch line pair through a predetermined gate operation, which is stored on the magnetic walls of the strip magnetic domains 13.
The stored information is erased, as the case demands. In the Bloch line memory device, an erasing command is applied to the controller 17. The controller 17, upon receipt of the erasing command, supplies a predetermined current to a predetermined conductor and the magnetic circuit 16 to accomplish an erasing operation. Then, the operation in the controller 17 is generally advanced in the order as shown in FIG. 2. In the conventional technique, the Bloch line pair corresponding to information to be erased is chopped, in the state where it is included in a magnetic bubble domain from the head of a stretched stripe domain 13. Thus, the information erasing is completed with erasing the chopped magnetic bubble.
Meanwhile, the chip 12 includes many stripe domains 13 serving as storage loops arranged in parallel between the writing/propagation line (major line) 14 and the read-out/propagation line (major line) 15, and the chopped bubble domain is propagated along the major line 15 as in the conventional magnetic bubble memory device and erased by the bubble erasure section 18 provided at the end portion of the major line 15. Therefore, as shown in FIG. 2, in the prior art technique, it was necessary to erase the bubble domains successively chopped in the read-out/propagation line by repeating the bubble domain propagation and the bubble domain erasure.
The number of the chopped bubble domains is equal to that of the storage loops so that this repeating operation took a long time, which made it impossible to operate the conventional Bloch line memory at a high speed.
Further, in the prior art technique, since the end portion of a stripe domain is chopped for an erasure operation, it was necessary to shift to-be-erased Bloch lines to the end portion of a storage loop (stripe domain) and to erase them. To this end, it is necessary to bring the storage section and the erasure section close to each other. However, the magnetic field necessary for the erasure operation is so strong that it will necessarily influence the Bloch lines existing in the magnetic wall. Thus, if the erasure section is located in the neighborhood of the storage section, the other Bloch lines existing in the storage section are influenced. For example, the stored information may be inverted ("0".fwdarw."1" or "1".fwdarw."0") or undesired information will be written.
To prevent this, it is necessary to carry out the erasure operation at the position separated from the storage section by shifting the to-be-erased Bloch line pair to the end portion of the stripe domain constituting a storage loop and thereafter stretching the stripe domain using a technique of e.g. varying the bias vertical magnetic field. However, this method is inconvenient in that in stretching the stripe domain, a gyroscopic force is exerted to the to-be-erased Bloch line pair at the head of the stripe domain and the Bloch line pair is shifted from the end portion of the stripe domain to a side thereof. This provides a difficulty in that even if the head of the stripe domain is chopped, the to-be-erased Bloch line pair is not taken out together with the bubble domain, thereby making it impossible to erase the information.